Bogus Hi-Fi Accessories
Doug Goncz
http://www.symposiumusa.com/products.shtml
An email copy of your post is welcome.
Yours,
Doug Goncz, Replikon Research, Seven Corners, VA (remove pee dot mil antispam)
http://users.aol.com/DGoncz
http://groups.google.com/groups?as_q=DGoncz
"Function, Funding, Form, Fit, and Finish"
Harold & Susan Vordos
" Doug Goncz " <dgo...@aol.comp.mil> wrote in message
news:20021028135535...@mb-md.aol.com...
My honest opinion? I think items offered are very nice, but of little to
no value regards listening quality. If you want good performance in sound
gear, spend your money on the things that make the noise, not the cute
little things that help you display them. I'd rather have a room full of
McIntosh electronics sitting on shelves without cases than lesser quality
gear sitting on great roller bearings, doing what, I do not know.
Harold
Brian Evans
acoustic environment can (a) be heard, and (b) make a difference. Anyone
who ever sat their record player on top of a speaker and cranked the volume
will attest that yes, mechanical transfer of energy can make a difference in
the acoustics. is it what this guy heard - "Just a word to thank you. I
just received the Sveltes for the Nagra amps. They look great. But again I
was not prepared for the sonic surprise. God what a change in sound. I never
expected these to bring such an enormous improvement. Wow. Everything just
bloomed. The timbres are way more natural, and the bass and midbass are now
clearly defined. You must have poured some magical powder or something into
those shelves."
M. B., Quebec
I'm going to go out on a limb and say "maybe" with a very high gain tube
amplifier with crappy feedback circuit design (maybe that describes the
Nagra). I'll say absolutely, under a record player (those vinyl things).
But a 5/8" thick piece of stainless under a cd player, or a speaker? I
don't think so...not till my solid 24c gold speaker cables come in, anyway!
Brian
"Harold & Susan Vordos" <vor...@tds.net> wrote in message
news:Bcgv9.4933$ko1.9...@kent.svc.tds.net...
Ted Edwards
> What is your opinion of the products here:
Your subject line says it all. Above all, don't fall for the "speaker
wire" crap. #12 two conductor side by side (or twisted) cord is every
bit as good. I proved this to myself and some students with time domain
reflectometer tests.
That stuff sells to the fools who spend good money on tube technology
and gold plated connectors.
Ted
Glenn Ashmore
high end DJ consoles for nightclubs. These things have big top surfaces
with three or four turntables inset into them. They have monitor
speakers mounted just above and are surounded by a few gazzillion watts
of speekers. To prevent feedback the turntables are mounted on pads
that are two 3/4" steel slabs with an inch of high density closed cell
foam sandwiched between.
The isolators would probably not be noticed in a home high-fi system but
they make a big difference to these DJs who are trying to sync up two or
three turntables and get a clear sound out to the audience at a couple
of hundred DB.
Doug Goncz wrote:
--
Glenn Ashmore
I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com
PLAlbrecht
anyway!
You want that wrapped in bear fur or plain?
:-)
Pete
Harold & Susan Vordos
news:3DBDAC...@telus.net...
Ha! LOL!! Like you, only without any technical testing, I long ago
concluded that these high priced speaker cables were a joke, intended to
separate me from my hard earned money. In answer to that, I bought a
roll of #12 clear stranded appliance cord from an electrical distributor and
will be using that for my speaker leads in the new house we're building. I
prefer to not mention any trade names, but the wire looks suspiciously like
one of the ones we have heard of the most.
I run a 300 amp RMS solid state McIntosh amplifier and power a couple sets
of JBL speakers, so I do use the horsepower. I'm more than convinced that
the gold plated connectors add little to my listening pleasure aside from
preventing, at least on the short term, oxidized connections. Unless
copper alloy connectors have a nickel plate under the gold, the gold will
slowly migrate into the copper alloy and the benefits of the gold are lost
anyway. The benefit loss is the same for very thin gold plate. It usually
abrades away if the connections are made and broke a few times, leaving one
with very expensive common fittings with gold everywhere except for where it
does some good.
Harold
Larry Jaques
recycled pixels stating:
>What is your opinion of the products here:
>
>http://www.symposiumusa.com/products.shtml
Crockachit, mon. The need for rubber pads, et al,
went out with the use of turntable arms which are
the only thing capable of picking up the vibration
from the speakers. Pray tell, how do they eliminate
the vibration coming in from the sides of the cases
of all the components if they're so nasty?
Blasted newfangled snake oil peddlers, I swear.
------------------------------------------------------
I survived the D.C. Blizzard of 2000...from California.
----------------------------
http://www.diversify.com Comprehensive Website Development
--------------------------------------------------
vince
And what the hell is wrong with tubes? STILL used in many applications -
like most big TV transmitters!!!
Tim Williams
news:20021028165958...@mb-fu.aol.com...
> >> I don't think so...not till my solid 24c gold speaker cables come in,
> anyway!
>
> You want that wrapped in bear fur or plain?
And decorated in Bald Eagle feathers, please.
Tim
--
"Hey, back in high school I was voted most likely to be a Hillbilly,
mental patient or Chimpanzee!"
- Homer Simpson
Carl Byrns
Made from leftover "Miracle Pain Relieving Magnets", no doubt.
Some audiophiles are real suckers for that kind of stuff.
- Carl (I have a pair of Klipsch LaScalas and know how to use them)
GTO69RA4
>
>Tim
I find Spotted Owl brings out the 6.75 to 6.77 KHz range much better.
GTO(John)
Ted Edwards
> And what the hell is wrong with tubes?
Nothing - when they are used in applications where they are the best and
most appropriate solution. Like the shaper (this is r.c.m.), they do
certain jobs better than any other currently available technology.
Audio (what this thread is discussing) is definitely not one.
I have been designing and building my own audio amps since the '40s. I
fought the undesireable properties of tubes when they were the only game
in town. I then played with and rejected the early transistors because
of poor noise performance and lousy power handling capabilities. This
all changed in the 60's when I could suddenly get better noise
performance, better power handling and lower distortion out of junction
transistors. When FETs came along all the band wagon jumpers wanted to
use them everywhere even where they were inappropriate.
My philosophy has been, since my pre-teens, to learn the property of
devices and use them were their fundamental properties and current state
of the art makes them the best solution to a particular problem. (I
haven't, personally, had an application for a thyratron in years.)
Ted
Dave Martindale
>And what the hell is wrong with tubes? STILL used in many applications -
>like most big TV transmitters!!!
Well, actually, solid state amps are taking over a lot of that market.
I recently had a tour of the transmitter facility for the local CBC TV
station, and got to look at the retired tube transmitters.
The replacement solid-state transmitters can't produce kilowatts of
power from a single active device like the tube unit did. Instead,
there are a bunch of modules each of something like 1 kW output.
They are all fed in phase with each other, and the outputs are combined
using a bunch of matching networks to give the power needed. If one
module fails, the transmitter continues operating with just a small loss
of power.
Dave
Dave Martindale
>Made from leftover "Miracle Pain Relieving Magnets", no doubt.
The local Princess Auto has a stack of "magnetic healing" thingies in
their surplus department. They point out it's easy to cut the things
open to get the magnets out.
Dave
Harold & Susan Vordos
----- Original Message -----
From: "Larry Jaques" <lja...@diversify.com>
Newsgroups: rec.crafts.metalworking
Sent: Monday, October 28, 2002 7:43 PM
Subject: Re: Bogus Hi-Fi Accessories
> On 28 Oct 2002 18:55:35 GMT, dgo...@aol.comp.mil ( Doug Goncz ) posted
> recycled pixels stating:
>
> >What is your opinion of the products here:
> >
> >http://www.symposiumusa.com/products.shtml
>
> Crockachit, mon. The need for rubber pads, et al,
> went out with the use of turntable arms which are
> the only thing capable of picking up the vibration
> from the speakers. Pray tell, how do they eliminate
> the vibration coming in from the sides of the cases
> of all the components if they're so nasty?
>
> Blasted newfangled snake oil peddlers, I swear.
Actually, you can have trouble with vibrations with a CD player as well. I
was shocked when I set up my system on a temporary basis with my CD player
sitting on top of a set of speakers. About the time I was pulling 300 watts
it started skipping, a strange experience considering they aren't usually
bothered by such things. I now have it sitting on an egg crate type foam
pad, about 2" thick which tends to isolate it adequately. I can't wait to
get the stereo room finished!
Harold
Gary Coffman
>And what the hell is wrong with tubes? STILL used in many applications -
>like most big TV transmitters!!!
Well, the *old* transmitters anyway. But Harris, the largest TV transmitter
manufacturer, hasn't built a tube type VHF transmitter in over 10 years.
Our 50 kW Goldline is all solid state. It is so reliable that we tend to forget
to go out and take a look at it. We've had *zero* lost air time since it was
installed 5 years ago. Our power bill has been sharply reduced (no filaments
to heat, much smaller cooling power requirements, etc). And there are *no*
critical tuning requirements for the PAs. It is simply linear and flat without
peaking networks of any sort. It is the most transparent high power amplifier
of any sort I've ever seen.
By contrast, the TT50H tube type transmitter it replaced required near
constant attention. Tube replacement was an expensive routine fact
of life. Plate blocker arc-overs were commonplace. Tuning was critical,
and changed as the tubes aged. Blower maintenance was a continuing
chore. Etc.
The solid state transmitter also has "soft fail". That means if a module
fails, the transmitter continues operating at only slightly reduced power
(a drop of -0.138 dB per failed module). Modules can be *replaced hot
while the transmitter is still on the air* too. Try that with a tube type
transmitter. (We had to maintain a *spare transmitter* in the tube days
so we could shut one down for maintenance. We don't have to do that
now.)
The highest DC voltage in the RF sections of the Goldline is 48 volts,
so it is *much* safer to work around than the old transmitter, which
used 12 kV on the plates. (Currents are comparatively huge, though,
so remove rings, watches, etc, when working on it hot.)
>http://www.mosweb.com/tp3.htm
To be kind, most of the information on that page is outdated. The rest
of it is just wrong. Example, no recent comsat has been launched with
TWTs. They're all solid state now, and higher powered than the older
sats too, nominal transponder downlink power is now 50 watts instead
of the 12 watts with TWTs. That's possible because solid state amps
have *much* lower parasitic power requirements, so the very limited
solar panel power is used more economically to make RF.
The satellite live trucks you see driving around also use solid state
transmitters (unless the truck is very old). They use a *pair* of transistors
to produce 300 watts at Ku band (12 GHz). Unlike TWTs, they're also
nearly immune to the problems of road shock and vibration, which could
and did snap the helix of (very expensive) TWTs while driving to a site.
There's very little use left for power tubes in broadcasting. Continental
does still make klystrode transmitters for UHF, but they haven't sold many
compared to the solid state models offered by other manufacturers. The
high operating power costs, relatively short tube life, and reduced reliability
has obsoleted vacuum tubes for this application within the last decade.
(The up front costs of the two types of transmitter are similar thanks to the
continuing decline in solid state component costs, but the operating costs
of the tube type are overwhelmingly larger. Payback, thanks to savings in
operating costs, can be as little as two years when replacing a tube type
transmitter with a solid state one. That makes even the most cheapskate
management sit up and take notice. Our entire 22 station chain converted
to all solid state in the last 5 years. Even though we know we'll be shutting
down the analog transmitters in the near future, we're already enjoying a
serious cost savings while improving on air reliability and signal quality
markedly.)
Tubes can't do anything that can't be done better using solid state, except
perhaps producing more distortion and coloration of the signal. That should
*never* be the objective of a high fidelity amplifier. By definition, the only
signal distortion a linear amplifier should produce is a larger amplitude for
the output signal. (An argument can be made for tube distortion when taken
as *part of a musical instrument*, but no such argument can be made for
high fidelity reproduction equipment.)
There is so much BS in the "high end" audio community that it is sickening.
The very few genuine improvements produced by that community have been
lost in the noise of all the BS artists selling pixie dust.
Gary
GD
<http://www.elecdesign.com/Articles/Index.cfm?ArticleID=719>
GD :-)
--
DejaVU
<20021028135535...@mb-md.aol.com>:
> What is your opinion of the products here:
>
> http://www.symposiumusa.com/products.shtml
neato snake oil way to make money off idiots who will buy anything
jeepers Doug, this is the kind of thing guys like us design so we can
laugh at the morons that fall for the advertispeak and make us rich.
the only thing that benefits from isolation is a turntable, and then
only under HIGH SPL levels, normal 80-85db listening levels will
never cause enough feedback to matter, doubt it's even measurable.
sure, a soft floor, or large shelf with flexible mountings, a wobbly
table etc, will affect feedback levels, but more likely will just
skip when you walk on the floor. can you hear it? nooooo
what you CAN easily hear are the motor and turntable bearings
rumbling. fix those first
PS:
I moonlight in sound reinforcement and play one on the internet.
I've seen sound levels vibrating a stage such that all the
footlights wobble and give an interesting display. I've seen how
people dancing on a soft floor causes a turntable to skip. I've
listened to high end audio systems, and low end, and nothing ever
needed ball bearings in the feet to make it sound better!
in short, don't waste your money, a sturdy and sensible shelf
mounting is all you need.
swarf, steam and wind
--
David Forsyth -:- the email address is real
Molder of church sound, photographer, metalworker etc. /"\
http://terrapin.ru.ac.za/~iwdf/welcome.html \ /
ASCII Ribbon campaign against HTML E-Mail > - - - - - - -> X
If you receive email saying "Send this to everyone you know," / \
PLEASE pretend you don't know me.
DejaVU
<20021028165958...@mb-fu.aol.com>:
hehe
actual advert seen in a local rag
"gold plated battery connectors to improve your modbile audio
enjoyment"
gimme a break
Peter H.
>>
The replacement solid-state transmitters can't produce kilowatts of power from
a single active device like the tube unit did. Instead, there are a bunch of
modules each of something like 1 kW output. They are all fed in phase with each
other, and the outputs are combined using a bunch of matching networks to give
the power needed. If one module fails, the transmitter continues operating
with just a small loss of power.
>>
There are several approaches.
For AM radio, the best design is an array of current sources, which are
simultaneously turned on or off at: 1) the (assigned) carrier frequency, and 2)
the (modulating) audio frequency (which is digitized to 12-bits).
The most-significant bits operate at one voltage, the least significant bits
operate at a much lower voltage.
Failures are very uncommon.
Efficiencies are now so high that many stations have to supply supplementary
heat to their transmitter sites.
Previously, reject heat was used to heat the transmitter building in winter.
Larry Jaques
<vor...@tds.net> posted recycled pixels stating:
Damnit, Harold. DON'T SEND EMAIL when you post the
blasted message to the group.
>> Blasted newfangled snake oil peddlers, I swear.
>
>Actually, you can have trouble with vibrations with a CD player as well. I
>was shocked when I set up my system on a temporary basis with my CD player
>sitting on top of a set of speakers. About the time I was pulling 300 watts
>it started skipping, a strange experience considering they aren't usually
>bothered by such things. I now have it sitting on an egg crate type foam
>pad, about 2" thick which tends to isolate it adequately. I can't wait to
>get the stereo room finished!
You should know better than to set stereos on speakers,
especially those with mechanical components inside, when
you crank 'er up.
----------------------------------------------
CAUTION: Driver Legally B l o n d (e)
http://www.diversify.com Web Database Development
=======================================================
Ted Edwards
> The local Princess Auto has a stack of "magnetic healing" thingies in
> their surplus department. They point out it's easy to cut the things
> open to get the magnets out.
What sort of magnets? I'm looking to get a few rare earth magnets for
the shop.
Ted
Ted Edwards
> Actually, you can have trouble with vibrations with a CD player as well. I
> was shocked when I set up my system on a temporary basis with my CD player
> sitting on top of a set of speakers. About the time I was pulling 300 watts
> it started skipping, a strange experience considering they aren't usually
Nearby nuclear blasts or Richter 8 earthquakes could presumably cause
similar problems.
BTW, do you have an oscilliscope? I would love to see the results of an
actual waveform from a putative 300 watt audio amplifier playing, say,
the 1812 overture! The bigest amplifier I've ever built was 50 watts
peak per chanel and it caused problems:
"
Some comments on power amplifiers for audio use.
Ratings:
I am not designing for the market place and therefore have
absolutely no interest in inflating power ratings. I rate my
amplifiers in terms of peak power before clipping since:
a) Unlike average power, it is independent of waveform. "RMS
power" is a meaningless concept.
b) all my designs have been capable of maintaining their peak
output indefinitely at any frequency from DC up to 50 or 100KHz.
Clipping level is determined by regulated power supplies and current
limiting for protection.
Back in the mid-60s, a technician working for me was in a band with
his brother. Bro' played bass guitar and wanted an amp. I had
designed a 50 Watt peak per channel stereo amplifier for my students
to build as a lab exercise. (Really got their attention.) I
suggested they use this design for the bass guitar. My tech said
there was no way 50 w was enough so I made a deal: You buy the parts
and build it. If it isn't enough, I will design a more powerfull one
and pay for the parts. This was too good to resist. They bought
special speakers claimed to be suitable for bass guitar use and rated
at 150 W and built suitable enclosures for them and built the amp. At
the first gig, they blew a speaker. They returned it to the shop who
gave them another under warranty. When they blew a second one, the
shop insisted they send it back to the manufacturer before they would
do anything. The manufacturer's response (and I quote) was "What
makes you think you can put 50 real watts into a 150 w rated speaker?"
When they eventually got a speaker system that could take it, they
were quite happy with the amplifier.
Output Impedance:
I use complementary compounds (not Darlingtons) in push-pull
for my output stages. These compounds have the property that their
output impedance is approx. 30 ohms divided by the emitter current of
the second times the beta of the first. For example, with an idling
current of only 20 ma (pretty low) and a driver beta of 50, the
amplifier open loop output impeadance at idle is only 30 milliohms.
Note that this is _before_ any feedback is applied. This is unlikely
to cause any measurable distortion in a class AB type amplifier.
Ted
Ted Edwards
signal degredation. These were wires twisted loosely together and
wrapped with a bit of masking tape. Given time and oxidation, it is
possible for these to produce rectification and/or impedance variation
due to vibration. However there is no way a soldered or properly
crimped splice will be detectable at audio frequencies.
Ted
jim rozen
peter...@aol.comminch says...
>Previously, reject heat was used to heat the transmitter building in winter.
And, probably in the summer, too! :^)
Jim
===================================
please reply to:
JRR(zero) at watson dot ibm dot com
===================================
Harold & Susan Vordos
"GD" <da...@wmch.edu> wrote in message news:3DBE8A6F...@wmch.edu...
Thanks, John. Good article.
Harold
Harold & Susan Vordos
parallels the above. One of our microphone connections had oxidized and
was behaving as a detector. I was accused of having a radio running during
one of the performances. Only after I found the "detector" and re-soldered
the connection was I exonerated. Connections (splices) matter, but only
when they are not proper. So long as there is a solid connection and it
doesn't change the impedance of a circuit, for the life of me I can't see
how it matters at audible frequencies. Chalk that one up to a stupid
person that thinks when a bird looks, quacks and walks like a duck, it's
most likely a duck.
Harold
Harold & Susan Vordos
"Larry Jaques" <lja...@diversify.com> wrote in message
news:csatru4svpgq55ega...@4ax.com...
> =======================================================
Yeah, sorry about the email thing.. Actually, in error I sent the reply to
you first. I wanted to post it to the group, so had to copy it and send it
a second time so it could get posted. I'll do my best to avoid doing
that again, but hope you understand if I screw up the same way. Seems to be
one of my weaknesses, probably force of habit. At any rate, my apologies.
As to where things sit at the moment (stereo), we're doing the best we can
with what we have. The electronics simply have to dwell atop the speakers,
for there is no other place to put them. We're living in the shop while we
build our house. Not exactly a luxury resort, but it sure beats living in
our travel trailer. :-)
Harold
Dave Martindale
I didn't buy any of them to try it. However, the magnets didn't seem to
be terribly strong, so I suspect they aren't rare-earth types.
Princess Auto does sell surplus hard drive magnet assemblies, with both
the magnets and pole pieces. Those *are* very strong, but you have to
disassemble them yourself, and the magnets are arc-shaped.
My favourite source for rare-earth magnets is Lee Valley. They sell a
variety of sizes in disc, rod, and donut shapes, as well as machined
metal cups to install the disc ones in.
And they are strong. A stack of 3 of the half-inch diameter ones
dropped into a piece of ordinary half-inch copper pipe held vertical
takes 5 seconds per foot to descend through the pipe.
Dave
Harold & Susan Vordos
I'm afraid you have me at a disadvantage in that I have absolutely no
electronics education aside from the radio and electronics class I took in
high school. While I have all the faith in the world in the literature of
McIntosh, perhaps it is they that need to read your post, not me. I don't
have any doubts about what you have to say, but I'm reasonably sure that the
ratings of their equipment is not exaggerated. For example, and you
should really enjoy this one: Their 1000 watt amplifier is capable of being
used as a welder. Sounds weird, alright, but it has 180 amperes available
at the output. That it could provide that kind of amperage on an ongoing
basis or not I do not know. McIntosh, to my knowledge, does not rate their
equipment such that you can't get what they claim.
Don't doubt that the amplifier I have can put out 300 watts. Yes, I do
understand how much noise that can make. I do realize that you can fill a
large room to the uncomfortable level with 10 watts. I also understand
that useable wattage and rated wattage are not one and the same. Years
ago, McIntosh used to provide clinics for analysis of performance of their
equipment. These clinics were provided at no cost to the owners of their
equipment, and when a tube type amplifier was found to perform at less than
their rated performance, tubes were replaced until it met specs. McIntosh
covered the cost of the tube replacement, it cost the consumer absolutely
nothing, and it didn't matter how old the equipment was, nor if it was in or
out of warranty.
The amplifier I own at this time is a McIntosh 2300. That means that it
will put out 300 watts per channel (their claim, not mine) and do it at the
level of distortion at which the amplifier is rated, which, by modern
standards, is not all that great. Considering the amp was built in the mid
70's, however, it is as good as it got at that time. Current amps are
rated at only .0005% distortion, whereas this one is rated at .05%
distortion at rated output. At the clinic, amplifiers were hooked to HP
test gear and loaded. Amps were always tested beyond rated output, and I
have a printed graph from the last clinic in which the amplifier is shown to
meet specs at 409 watts per channel. I have no way of knowing if they
were on the level, again, claiming my ignorance of electronics as the
reason. Maybe I'm too easily impressed with an amplifier that can make so
damned much sound that you can't be in the room with it, no matter the size
of the room, but I believe what Mc has to say. I see no reason for them to
have lied to the public for years. Their only objective was to produce and
sell sound reproduction gear that was of the highest quality. They were so
well known and produced such high quality that their power supplies found
use in industry. I recall seeing Mc75 amps at Sperry in the electronics
department. I was trained as a machinist at Sperry.
Yes, I do have a scope, but it is a McIntosh MPI-4, a scope they produced
for a short period of time. The scope is capable of taking its signal
directly from the amplifier (and the preamp, as well as from the tuner), so
one can tell what is going on at the output stage. I have the 1812 on
record, a direct to disk recording, in which the cannon shots are so great
that my turn table won't track the shot properly. The literature with the
record claims that only about 5% of the turntables on the market at that
time were capable of tracking the record. I had hoped my Thorens TD 125
would be up to the task, but it was not. I was running a Supex moving coil
cartridge at the time, tracking at under 2 grams. Changing tracking weight
made no difference, I could not track the vinyl disk. The scope test in
this instance would be of no value, but it sure as hell would be if a CD was
employed.
The next time you drive to the States, heading down the I-5 corridor, you
might enjoy stopping off to see the setup. If you're not familiar with
McIntosh, you might get your eyes opened. Hard to say.
Harold
Larry Jaques
<vor...@tds.net> posted recycled pixels stating:
>Yeah, sorry about the email thing.. Actually, in error I sent the reply to
>you first. I wanted to post it to the group, so had to copy it and send it
>a second time so it could get posted. I'll do my best to avoid doing
>that again, but hope you understand if I screw up the same way. Seems to be
>one of my weaknesses, probably force of habit. At any rate, my apologies.
You're about the tenth guy from RCM to do that since I
logged in a couple months ago, so it remains a sore point
and generalized hostility. :( Apology readily accepted.
>As to where things sit at the moment (stereo), we're doing the best we can
>with what we have. The electronics simply have to dwell atop the speakers,
>for there is no other place to put them. We're living in the shop while we
>build our house. Not exactly a luxury resort, but it sure beats living in
>our travel trailer. :-)
Put the stereo in the travel trailer and go there
when you want music?!? What about the free used
cinder block/recycled board shelving we all made
when we were teens? Or hang the speakers on the
wall while leaving the stereo where it is? (I
couldn't do that with my old 75lb Bose 501's,
but most people could with their generic speakers.)
How about drilling holes in the studs and putting
metal rods + shelving to hold the stereo or spkrs?
Where's your imagination, dude?
Larry Jaques
recycled pixels stating:
www.leevalley.com has 'em, Ted. Pgs 136 & 137 of the new catalog.
Dozens, in all styles. (std disclaimer applies)
Bob May
Bet that stuff can turn my 5 tube radio with its 3" speaker into a Stereo
System with nice big speakers just by buying all of that wonderful stuff! !
!
Gotta get it all and the radio will really sound nice and clear on that
station 250 miles away that I love to listen to.
Thing is, how does it do that?
--
Bob May
Global WARMING???
What I want to know is when I can start growing wheat in Greenland again!
Harold & Susan Vordos
ROFLMAO!!!
Have you ever tried to hang a JBL Paragon on rods from the wall? (You do
know what the Paragon is, don't you?) I run a Paragon and a set of JBL
C-50 Olympus speakers (S8R components) in tandem. NO way will they fit
in the travel trailer, and the weight is far greater than I'd like hanging
off the wall. The combined weight of these speakers is in the
neighborhood of 700 pounds and they take up over 16 feet of space. I'm so
crowded that I have the C-50 speakers sitting on top of the Paragon, and the
electronics sitting on top of the C-50's. It works, but it doesn't replace
the stereo room, not by a long shot. Oh yeah, the amp weighs in at 128
pounds. Weight in and of itself limits me to a great extent.
I thought stacking the components the way I did was being creative! (Where's
your imagination, dude?) Stop by for a look. We're crowded. REAL
crowded. :-)
> You're about the tenth guy from RCM to do that since I
> logged in a couple months ago, so it remains a sore point
> and generalized hostility. :( Apology readily accepted.
Cool.. Part of my problem in this area is my lack of computer skills.
I'm constantly going back to correct stupid things. What I know about
computers wouldn't fill a small thimble. What I am is a machinist that
loves sound gear. Don't claim to be an electronics expert, but I do the
best I can. I screw up on the computer, just hope others will be a little
forgiving of those of us that lack high levels of skills and expertise.
You seem to qualify! :-)
Harold
jrla...@shell.golden.net
Carl Byrns <carl....@verizon.net> wrote:
>
>Made from leftover "Miracle Pain Relieving Magnets", no doubt.
>
>Some audiophiles are real suckers for that kind of stuff.
I've noticed a trend in that the degree of gullibility tends to be
proportional to the amount of money invested in their system. That tends
to also be true with their hearing ... the more they spend the better they
can hear!
--
john R. Latala
jrla...@golden.net
jrla...@shell.golden.net
Bob May <bob...@nethere.com> wrote:
>WOW ! ! ! WOW ! ! ! WOW ! ! ! WOW ! ! !
>Bet that stuff can turn my 5 tube radio with its 3" speaker into a Stereo
>System with nice big speakers just by buying all of that wonderful stuff! !!
Reminds me of that joke about the guy who bought about a dozen or so
mileage doodads for his car. Since each one promised a ten percent
reduction in mileage his only problem now is that every hundred or so
miles he has to siphon gas OUT of the tank because it keeps refilling
itself! :-)
jrla...@shell.golden.net
Have you checked the Lee Valley catalog?
Mark Winlund
"Harold & Susan Vordos" <vor...@tds.net> wrote
> I run a 300 amp RMS solid state McIntosh amplifier and power a couple
sets
Hey Harold.... are those amps gas or diesel powered? My welder only puts
out 250 amps.... <g>
Mark
Harold & Susan Vordos
"Mark Winlund" <ma...@maxmachine.com> wrote in message
news:urubfhd...@corp.supernews.com...
You'd think by now I'd know the difference between amps and watts, but the
proof of the fool is printed here for all to see!
OK, lets start over, I run a 300 WATT RMS solid state McIntosh amplifier
and power a couple
sets etc., etc..
Nice catch, Mark. I read that damned thing after posting it and it looked
great to me! :-) (But then, what do I know?)
Harold
Jeffry Johnston
: Ratings:
: I am not designing for the market place and therefore have
: absolutely no interest in inflating power ratings. I rate my
: amplifiers in terms of peak power before clipping since:
: a) Unlike average power, it is independent of waveform. "RMS
: power" is a meaningless concept.
: b) all my designs have been capable of maintaining their peak
: output indefinitely at any frequency from DC up to 50 or 100KHz.
: Clipping level is determined by regulated power supplies and current
: limiting for protection.
: The manufacturer's response (and I quote) was "What
: makes you think you can put 50 real watts into a 150 w rated speaker?"
Can you re-phrase that in voltage please? :)
My 4 ohm speakers are rated at 100dB/watt/meter.
On the ten volts-ac scale when the meter is dancing around 5 volts
I need ear plugs to be sitting in front of the speaker reading the
voltmeter.
Are the "real watts" you're talking about simply ohm's law?
: Output Impedance:
: I use complementary compounds (not Darlingtons) in push-pull
: for my output stages. These compounds have the property that their
: output impedance is approx. 30 ohms divided by the emitter current of
: the second times the beta of the first. For example, with an idling
: current of only 20 ma (pretty low) and a driver beta of 50, the
: amplifier open loop output impeadance at idle is only 30 milliohms.
: Note that this is _before_ any feedback is applied. This is unlikely
: to cause any measurable distortion in a class AB type amplifier.
: Ted
I bought a noisy, used power amp and sent it back to the factory
in Florida and they fixed it and updated it and I have almost $600
in it. I never could have afforded it otherwise. Mid 80's.
It's an Acoustat (Trans-Nova) twin 200, mos-fet
200 "watts" into 8 ohms and 325 @ 4 ohms, damping factor over 1000,
165 volt/micro-second slew rate and 400K Hz band width @ -3dB
They claim a full rail to rail capability, the rail is 72 volts?
How does it compare to your 50 "real" watter?
The book that goes with it explains how to set the bias and DC offset.
Are you interested in a copy of the book?
Alvin in AZ
Jeffry Johnston
little yellow head phones and walkmen...
If you have regular plated headphone jack (the model from
walmart) and the jack moves, it's noisy and if you have the
same model with the gold jacks (from circuit city) and it
moves it's not noisy. No kidding. Even after they get old.
I have several pair over several years to base my BS on.
I used to give them away to kids I knew like I was crazy
or something. Are the voices in my head bothering you?
Alvin in AZ
Gary Coffman
>"Ted Edwards" <Te...@telus.net> wrote in message
>news:3DBEBD...@telus.net...
>>
>> Ratings:
>> I am not designing for the market place and therefore have
>> absolutely no interest in inflating power ratings. I rate my
>> amplifiers in terms of peak power before clipping since:
>> a) Unlike average power, it is independent of waveform. "RMS
>> power" is a meaningless concept.
>> b) all my designs have been capable of maintaining their peak
>> output indefinitely at any frequency from DC up to 50 or 100KHz.
>> Clipping level is determined by regulated power supplies and current
>> limiting for protection.
>>
>> Output Impedance:
>> I use complementary compounds (not Darlingtons) in push-pull
>> for my output stages. These compounds have the property that their
>> output impedance is approx. 30 ohms divided by the emitter current of
>> the second times the beta of the first. For example, with an idling
>> current of only 20 ma (pretty low) and a driver beta of 50, the
>> amplifier open loop output impeadance at idle is only 30 milliohms.
>> Note that this is _before_ any feedback is applied. This is unlikely
>> to cause any measurable distortion in a class AB type amplifier.
>>
>> Ted
>>
>Ted,
>I'm afraid you have me at a disadvantage in that I have absolutely no
>electronics education aside from the radio and electronics class I took in
>high school. While I have all the faith in the world in the literature of
>McIntosh, perhaps it is they that need to read your post, not me. I don't
>have any doubts about what you have to say, but I'm reasonably sure that the
>ratings of their equipment is not exaggerated. For example, and you
>should really enjoy this one: Their 1000 watt amplifier is capable of being
>used as a welder. Sounds weird, alright, but it has 180 amperes available
>at the output. That it could provide that kind of amperage on an ongoing
>basis or not I do not know. McIntosh, to my knowledge, does not rate their
>equipment such that you can't get what they claim.
McIntosh rates their amps in terms of "RMS power". Now as a physicist
will tell you, that's a nonsense term. But what it means in the audio world
is that their power ratings are the *average power* for *continuous pure
sinewave signals* (which can be calculated using RMS values for voltage
or current, hence the term). In effect that's the same thing that Ted is saying
when he says his amp can maintain 50 watts "peak output indefinitely".
So since the two of you are talking about the same thing using different
words. It is safe to say that your 300 watt McIntosh is 6 times more powerful
than the 50 watt amp he described.
However, how that relates to advertised wattage of most consumer audio
equipment is a bit more elusive. Most audio manufacturers use a measure
called IHF power. Their power ratings are for single transient peaks, not
steady state output. That makes some sense, because music is rarely
composed of just pure sinewaves. It is full of high amplitude transients of
various sorts.
You lose fidelity if the amp can't faithfully reproduce those transient peaks.
So the power measure you're really interested in is the maximum unclipped
transient output the amplifier can produce. The IHF rating system is supposed
to approximate that more realistically than the RMS measure. In other words,
you can build a much cheaper amp if it only has to handle transients at high
peak levels.
A crude rule of thumb says that peak to average ratio of speech is about
8 to 1. That doesn't exactly hold for music, but it is roughly the way IHF
power is calculated. In other words, dividing an IHF wattage rating by
8 should give you RMS watt ratings.
But this is only a crude rule of thumb because it doesn't fully consider
heatsink capacity, power supply secondary current ratings, etc. Basically,
it is only the maximum single event peak current that the output devices
can draw from the power supply filter capacitors for a period approximating
a high frequency transient event in the signal. Thus an amp with a 300
watt IHF rating could easily be only a 10 watt RMS amp.
It is pretty safe to say that an IHF rated 1000 watt amp would be *much*
wimpier than a 1000 watt RMS rated amp. But you probably can't turn the
RMS amp up louder than the IHF rated amp and still call it high fidelity,
because it would start to clip high frequency transients then.
It could certainly produce more sound on a sustained basis, but it would
be distorted sound due to transient clipping. OTOH, you can really tell the
difference down in the bass region. The RMS rated amp will have much
more guts there for delivering sustained power, and it'll clearly show in a
listening test.
It is also interesting to note that a 1000 watt amp which can source
180 amps has an output impedance of approximately 31 milliohms.
That's virtually the same design impedance as Ted used for his
amp, which says that the designers of the McIntosh amp and Ted
were thinking along the same lines when they came up with their
designs.
McIntosh (and Crown) make very robust amplifiers that run cool
and last a long time. You'll find them in many professional settings.
We've got a bunch of them at our stations. They are virtually never
cranked "all knobs to the right" in our usage, though, because we
don't want to *ever* drive them into transient distortion.
Example, a 300 watt RMS amp would rarely be asked to deliver more
than about 10 watts average, leaving plenty of headroom to handle
transient peaks in the music without distortion (about 14.8 dB). Ten
watts average is a *lot* of audio. With reasonably efficient speakers,
it can be painful.
Gary
Mark Winlund
"Harold & Susan Vordos" <vor...@tds.net> wrote
> OOPS!
>
It probably was wishfull thinking..... "I have 300 amps (amplifiers)
powering my stereo system...
Note to NG: I've seen Harold's setup, and it is quite the system. Serious
stuff.
Mark (whose stereo comes from Radio Shack)
Ted Edwards
> parallels the above. One of our microphone connections had oxidized and
> was behaving as a detector. I was accused of having a radio running during
> one of the performances. Only after I found the "detector" and re-soldered
> the connection was I exonerated. Connections (splices) matter, but only
The first radio I ever built (mid to late '40s) used an old earphone, a
coil wound with wire scrounged from a dead small motor and a detector
consisting of a safety pin with its point resting on a rust spot on an
old razor blade.
Ted
Ted Edwards
Do they actually state "300 WATT RMS"? Do the use the term "RMS"?
Ted
Ted Edwards
> My favourite source for rare-earth magnets is Lee Valley. They sell a
> variety of sizes in disc, rod, and donut shapes, as well as machined
> metal cups to install the disc ones in.
I know. I just have to get a round tuit.
Ted
Harold & Susan Vordos
a crystal set. My only question is how did those that went before us
discover such things?
Harold
Harold & Susan Vordos
mentioned that at the clinic my 300 WATT (not amp) amplifier was found to
meet specs at 409 watts per channel, both channels running. It is tested
at both ends of the listening spectrum.
I think that the post that Gary so nicely provided helps explain why RMS is
quoted. To me, all it tells me is that I have available that amount of
useable wattage, which means nothing more than my system will break concrete
and do a nice job of it.
Would you like to see a scan of some of the literature pertaining to
McIntosh gear? I still have all the paperwork that came with my
electronics, along with some of their advertising brochures. I'd never
have known about RMS had it not been for McIntosh, for I am not an educated
person and get lost very quickly when it comes to electronics.
By the way, the McIntosh of old provided a 3 year warranty for their goods,
but when you registered the items it was not unusual for them to send a 5
year certificate. Didn't mean much, anyway, for if you took any of their
equipment to a clinic and it didn't work, it was repaired at no charge, and
that included tube replacement for the old gear that could have been years
out of warranty. They really took care of the consumer. Can you imagine
service like that today?
Harold
Brian Evans
Brian
"Harold & Susan Vordos" <vor...@tds.net> wrote in message
news:kfWv9.7253$ko1.1...@kent.svc.tds.net...
Ted Edwards
> Can you re-phrase that in voltage please? :)
My 50W amp was designed to be used with 8 ohm speakers so it could put
out 20 volts at 2.5 amps into an 8 ohm load. The amp was both voltage
limited and current limited for the sake of reliability. With 4 ohm
speakers, you would be voltage limited and could only get 25 watts
peak. Note that this is 12.5 watts average power on a sine wave.
(There is no such thing as RMS power except in the writings of ignorant
marketing types.)
> On the ten volts-ac scale when the meter is dancing around 5 volts
Depending on the nature of the source (I assume music since you say the
needle is dancing), your meter is reading average voltage with scale
calibrated to read rms volts on a sine wave. This would suggest you are
getting (very roughly) 6 watts average power. Loud, isn't it!
RMS power is a physically meaningless concept. I'm sorry if this is all
very
confusing but it's not my fault. Some time in the late '50s or early
'60s
some thoroughly ignorant marketing type started using the term RMS
power.
While it could be defined mathematically, it is a completely meaningless
term physically. Let me explain.
Power is the rate of doing work. For a steady state DC circuit, this is
just
volts times amps. Introduce AC and/or transients and life gets more
complicated.
Let's start with instantaneous power. Instantaneous power is, not
surprisingly, instantaneous voltage times instantaneous current measured
at
the same instant. You cannot measure this on non-repetitive waveforms
with a
conventional meter. You need an appropriate oscilloscope with a low
resistance shunt for the current. It is also possible to do this with a
shunt, a small handfull of resistors, a couple of good op-amps, a fast
analog
multiplier and just about any oscilloscope.
Now lets assume you have that straight. Average power is defined as the
integral with respect to time of the instantaneous power divided by the
time
duration of the integration. i.e.
_ t2 _t2
1 | 1 |
Pav = --- | P(t)dt = --- |V(t)I(t)dt
t2-t1 |_ t2-t1 |_
t1 t1
Now, an interesting special case of no real interest in audio is the
case of a
pure sine wave into a resistive load. In this case, the voltage and
current
are in phase and the instantaneous power may be computed from
P(t) = (V(t)^2)/R
where V(t) is the instantaneous voltage and R is the load resistance.
Note
that this is not valid with a reactive load. If you do the integral for
this
case, you find that
( Vpk )2
Pav = (Vpk^2)/2R = ( --- ) / R
(1.414 )
Interestingly, if you calculate the square root of the time average
(mean) of
the square of a sinusoidal voltage, you find that it is the peak voltage
divided by the square root of 2. This makes the RMS (Root Mean Square)
voltage (or current, for that matter) of great interest in relating the
heating power (average power) of AC when compared to DC. This is where
the
concept of RMS quantities comes into play - RMS voltage and RMS
current. As
stated before, RMS _power_ is a meaningless concept.
I have always rated my amplifiers in terms of peak power output. This
is
determined by multiplying the peak output voltage obtainable without
clipping
by the maximum current the amplifier can deliver without current
limiting.
All my amplifiers in the last 40 years have used regulated power
supplies and
protective current limiting circuits making these quantities very well
defined. In addition, the heat sinking has been such that they could
operate
at this level indefinitely with any waveform. This rating is
independent of
the waveform being fed through the amp.
The least dishonest rating used in the hi-fi industry is the IHFM power
rating. This is measured as follows:
With no input, the power supply voltages are measured.
The units own power supplies are then replaced with laboratory
regulated supplies.
The output is meaured using a short tone burst (IIRC, 1KHz for
3msec)
at a signal level that generates 3% total harmonic distortion.
This "standard" takes advantage of the oft claimed idea that music has a
lot
of transients so the peak power is MUCH more than twice the average
power.
While this may be true for rock music, it is certainly not true for some
of
the better pipe organ recordings.
> It's an Acoustat (Trans-Nova) twin 200, mos-fet
> 200 "watts" into 8 ohms and 325 @ 4 ohms, damping factor over 1000,
> 165 volt/micro-second slew rate and 400K Hz band width @ -3dB
> They claim a full rail to rail capability, the rail is 72 volts?
>
> How does it compare to your 50 "real" watter?
I assume you mean 72 volts rail-to-rail i.e. +/-36V. In this case, if
it can swing rail-to-rail, that would be 324 peak watts into 4 ohms or
162 peak watts into 8 ohms.
> The book that goes with it explains how to set the bias and DC offset.
Hmmmm. A good design should, IMO, not require _any_ user setting of
these parameters but as long as it works, enjoy!
Ted
Dave Martindale
>I think that the post that Gary so nicely provided helps explain why RMS is
>quoted. To me, all it tells me is that I have available that amount of
>useable wattage, which means nothing more than my system will break concrete
>and do a nice job of it.
I think Ted was pointing out that the term "watts RMS" is misleading.
Taken literally, it means that the number would be calculated as the
square root of the mean square of the power in watts. It's certainly
possible to compute this, but it's meaningless for any purpose I know
of.
But that's not what amplifier manufacturers measure anyway. They
measure *mean* (average) power in watts over many cycles of the test
waveform. To do this this measure RMS *voltage* across a resistive load
and then use the usual V^2/R formula to convert to watts.
The reason they emphasize the "RMS" is that it's also possible to
calculate "peak power" using the peak voltage of the output waveform.
For a sine wave, this peak power is twice the mean power, so less
reputable amp manufacturers used to quote this to make their amps seem
more powerful than they are.
So measuring peak volts gives you peak power, which is mostly
meaningless. Measuring RMS volts gives you mean power, which is more
useful - but it is *not* RMS power. True RMS power is useless.
That's not all there is to power measurement, either - to be meaningful
the specs have to state what frequency range, what distortion level, and
what duration the power specifcation applies to. With the Mac amp,
the specs are probably 300W mean power with sine-wave drive from
20-20000 Hz with less than some particular level of distortion and for
continuous output.
There is also the IHF power standard which attempts to measure the
capability of an amplifier to amplify a short high-power peak without
clipping. If the amplifier has regulated power supplies capable of
maintaining voltage at full output power, this is no higher than the
continuous rating. But most amps use unregulated power supplies for the
output stages at least, and when playing music the voltage available is
quite a bit higher than it would be during a continuous-power test.
Thus it can often deliver one or a few cycles of higher-power output at
higher frequencies before the supply voltage droops. This is important
for being able to reproduce things like percussion instruments.
Dave
Tim Williams
news:U5Wv9.7252$ko1.1...@kent.svc.tds.net...
> To which I say "utterly amazing". I guess it was the poor man's version
of
> a crystal set. My only question is how did those that went before us
> discover such things?
Too much free time...in the POW camps.
(Or)
What, you never heard of metal-oxide rectifiers?
BTW I remember reading it's the blue on the razor blade that works best,
not rust. (Try it?)
Tim
--
"Hey, back in high school I was voted most likely to be a Hillbilly,
mental patient or Chimpanzee!"
- Homer Simpson
Tim Williams
> Mark (whose stereo comes from Radio Shack)
EeuuuUUU...
Hey, I've already made several amps from the junque you gave me.
What gives?
Tim Williams
WTF IS PMPO!?!?!?!?!?!?!?
Tim
--
"Hey, back in high school I was voted most likely to be a Hillbilly,
mental patient or Chimpanzee!"
- Homer Simpson
"Dave Martindale" <da...@cs.ubc.ca> wrote in message
news:appfd8$im1$1...@mughi.cs.ubc.ca...
<Can't think of appropriate text to quote>
Ted Edwards
> McIntosh rates their amps in terms of "RMS power". Now as a physicist
> will tell you, that's a nonsense term. But what it means in the audio world
> is that their power ratings are the *average power* for *continuous pure
> sinewave signals* (which can be calculated using RMS values for voltage
> or current, hence the term). In effect that's the same thing that Ted is saying
> when he says his amp can maintain 50 watts "peak output indefinitely".
Except that the IHFM standard uses tone bursts and other cheats - see my
post elsewhere in this thread. I've never had a commercial amp on the
bench that could maintain its maximum rated output for more than a few
milliseconds and damn few that could reach their rated output at all.
> However, how that relates to advertised wattage of most consumer audio
> equipment is a bit more elusive. Most audio manufacturers use a measure
> called IHF power. Their power ratings are for single transient peaks, not
> steady state output. That makes some sense, because music is rarely
> composed of just pure sinewaves. It is full of high amplitude transients of
> various sorts.
Unless you like pipe organs! :-)
> It is pretty safe to say that an IHF rated 1000 watt amp would be *much*
> wimpier than a 1000 watt RMS rated amp.
I assume you mean AVERAGE not RMS.
> difference down in the bass region. The RMS rated amp will have much
> more guts there for delivering sustained power, and it'll clearly show in a
> listening test.
If it was honest, it would not likely be using the term RMS power. If
it isn't honest then, ... .
> It is also interesting to note that a 1000 watt amp which can source
> 180 amps has an output impedance of approximately 31 milliohms.
The only meaningful output impedance of an amp is dynamic output
impedance since this is what creates speaker damping. This is dV/dI not
V/I and is usually (in a well designed amp) MUCH lower than V/I.
> That's virtually the same design impedance as Ted used for his
> amp,
The number I stated was open loop. Closed loop was in the micro-ohm
range.
Ted
Ted Edwards
> If you have regular plated headphone jack (the model from
> walmart) and the jack moves, it's noisy and if you have the
> same model with the gold jacks (from circuit city) and it
> moves it's not noisy. No kidding. Even after they get old.
Gold or silver plating on contacts makes some sense but gold plated wire
is just plain silly.
Ted
Tim Williams
> vince wrote:
>
> > And what the hell is wrong with tubes?
Nothing for me (glances at integrated stereo 6V6 Single-Ended (SE))..
> Nothing - when they are used in applications where they are the best and
> most appropriate solution. Like the shaper (this is r.c.m.), they do
> certain jobs better than any other currently available technology.
Shaper? As in VFD sort of stuff? I'd think SCRs (and two-way TRIACs)
would be better than a C6J any day..
(Heh, I have a C3J(?).. I'm going to dim the dining room chandilier(sp)
someday with it. :)
> Audio (what this thread is discussing) is definitely not one.
Ahem, I'll tell you to shut up right now, as that is an opinion, and
one that if allowed to get out of hand, well, err I messed that sentence
up eh.
..Can (and certainly has) cause(d) big trouble!
> I have been designing and building my own audio amps since the '40s. I
> fought the undesireable properties of tubes when they were the only game
> in town.
What undesirables? A properly designed AB1/2 amp can be as efficient
as a transistor amp, so it's not dissipation.
Size - sure, but who cares in a hi-fi system?
Heh, I noticed hi-fi's were big consoles in The Olden Days (I have
speakers from a Magnavox console), then shrunk to smaller tabletop
rectangles with moderate, honestly rated power output (of which I have
a good Onkyo example), and now they're bloating back up again, with
hugemongous 'PMPO' ratings as well! (Mom has one such thing.)
Not to mention the maze of digital controls, remote, internet probably,
etc.
> When FETs came along all the band wagon jumpers wanted to
> use them everywhere even where they were inappropriate.
Heh...sounds like tubes eh? ;-) Interestingly, FETs have a similar
curve to pentodes, don't they. (Maybe the people are saying something
about that curve...heheh)
> My philosophy has been, since my pre-teens, to learn the property of
> devices and use them were their fundamental properties and current state
> of the art makes them the best solution to a particular problem.
A good one.
> (I haven't, personally, had an application for a thyratron in years.)
I used one when last week or two ago I made a little curve tracer. :)
One of those lil' 2D21s Mark gave me.
BTW, Idunno - how's an SCR's negative-resistance characteristic? I know
they can be used for the same reason (sweep generator), but it just seems
to me they'd get stuck on. (Not like that didn't happen to me when I set
the bias too low on said 2D21.)
Spehro Pefhany
> It is now time in this thread to say,
>
> WTF IS PMPO!?!?!?!?!?!?!?
Peak Music Power Output. The audio equivalent of "Sears Horsepower" (and
then some). The magical specsmanship method that allows my offshore "120W"
computer speakers to be powered from a 9V 200mA AC adapter. ;-)
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
sp...@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
Brian Evans
Fender Bandmaster...:)
45 quite loud watts - rms, peak, or what have you tends to mean less when
you're overdriving the thing to hell and gone in the first place!
Brian
"Tim Williams" <tmor...@charter.net> wrote in message
news:us0j575...@corp.supernews.com...
Norman Yarvin
>RMS power is a physically meaningless concept. I'm sorry if this is all
>very confusing but it's not my fault. Some time in the late '50s or
>early '60s some thoroughly ignorant marketing type started using the term
>RMS power. While it could be defined mathematically, it is a completely
>meaningless term physically. Let me explain.
[good explanation of the proper ways to measure power snipped]
It should also be noted that if they *do* actually mean RMS power, then
the average power is lower. RMS power, though not a number that has any
practical implications, is well-defined mathematically (it's not just
that it 'could be defined', it is defined), and is always larger than
average power. Thus specifying "RMS power" presents an ideal opportunity
for cheating.
To illustrate, suppose that instead of running the amplifier at one watt
full time, one instead runs it at 10 watts for a tenth of the time, and
zero watts for the other 9/10 of the time. The average power is the
same, either way. But the RMS power? Well, for the amplifier running at
one watt, one squared is one, the mean of that is one, the root of the
mean is still one. For the amplifier running at 10 watts a tenth of the
time, 10 squared is 100, the mean square is 10, and the square root of
that is 3.16. Congratulations... you've just boosted the marketing specs
of your amplifier by a factor of three, by quoting "RMS power" instead of
the proper "average power", and by choosing a very "peaky" test signal.
--
Norman Yarvin norman...@snet.net
Tim Williams
news:10359615...@nnrp2.phx1.gblx.net...
> Can you re-phrase that in voltage please? :)
Do the math...
> My 4 ohm speakers are rated at 100dB/watt/meter.
> On the ten volts-ac scale when the meter is dancing around 5 volts
> I need ear plugs to be sitting in front of the speaker reading the
> voltmeter.
See below..
> Are the "real watts" you're talking about simply ohm's law?
'Real watts' are actual power. Work done.
A 100 ohm resistor plugged into the wall, the wall putting out 120VAC
RMS, will dissipate 144 watts. The power grid will be loaded down by
144W, and the resistor's temperature will ultimately rise in accordance
with it's dissipation of - yes, 144 watts.
If you have a sine wave, RMS AC voltage * ... current = true power.
Note that most voltmeters are peak or average reading, that is, a
rectifier and capacitor, with a scale calibrated to a sine wave,
usually 60Hz, to appear to read the correct voltage.
If you read an unusual waveform, perhaps one with one short, high peak
and lots of dead time, it just won't read the same.
(Example: flyback circuits.)
ARRRRummmm, back to the subject!!
Assuming your voltage reading was indeed the RMS AC voltage, then,
assuming the speaker is a 4 ohm resistor (hint: no ;), it was dissipating
5V ^2 / 4 ohms = 12.5W.
Since your speakers are rated at 100dB at 1W input as measured at a
distance of 1 meter, and 12.5W is maybe 11dB (my path correct?) up from
1W, so you must've been at 111dB, if you were 1 meter from the speaker!
Right?!? ;-)
- Yes, when dealing with RMS, power, resistive, etc., Ohm's law applies.
RMS is like DC in that way.
> It's an Acoustat (Trans-Nova) twin 200, mos-fet
> 200 "watts" into 8 ohms and 325 @ 4 ohms, damping factor over 1000,
> 165 volt/micro-second slew rate and 400K Hz band width @ -3dB
Nice...
Huh, I can get at least that much slew rate driving an inductor
on the breadboard... :)
> They claim a full rail to rail capability, the rail is 72 volts?
My Dad's Mac (he picked it up while in College in the 70s) is another
monster...120WPC at .01% THD or so, 20-20,000Hz into any impedance.
Interesting thing about it is, it has autotransformers on the output!
The schematic in the manual shows +/-42V rails, or 84V across.
Each is filtered with 2x10,000uF. :)
> How does it compare to your 50 "real" watter?
It seems to me all SS amps of reasonable performance (heck, even modern
power op-amps, I imagine) use the same complementary PP emitter (or
source) follower configuration.
Heck, if I had a 'PNP' 6AS7 (or 6C33C :), I'd do it too!
Instead I've gotta have weird feedback arrangements...oh well.
> The book that goes with it explains how to set the bias and DC offset.
> Are you interested in a copy of the book?
Me me me me me me :-)
Tim <-- seriously ignorant of most things solid state ;)
Tim Williams
news:10359200...@news-1.nethere.net...
> WOW ! ! ! WOW ! ! ! WOW ! ! ! WOW ! ! !
> Bet that stuff can turn my 5 tube radio with its 3" speaker into a Stereo
> System with nice big speakers just by buying all of that wonderful stuff!
!
Oh, you mean like Bose? :P
Tim
Steve Walker
reference to them), if you ever have to visit the emergency room at the
hospital, see if you can find the heart defibrillator, jump starter or
whatever it's called. Chances are you will see a Crown amp on the cart.
--
Steve Walker
res0...@verizonwallet.net (remove wallet to reply)
(Now Playing: Kick Start my Heart - Motley Crue)
signature design ŠLoco Jones
Dave Martindale
>> Can you re-phrase that in voltage please? :)
>My 50W amp was designed to be used with 8 ohm speakers so it could put
>out 20 volts at 2.5 amps into an 8 ohm load. The amp was both voltage
>limited and current limited for the sake of reliability.
So it will put out 50 W continuous if the waveform is a square wave, but
it's limited to 25 W of a single-frequency sine wave. Right?
Dave
Harold & Susan Vordos
"Brian Evans" <br...@uunet.ca> wrote in message
news:76Xv9.165510$C8.4...@nnrp1.uunet.ca...Brian,
I don't know if I can thank you enough for this link. I had no idea it
existed and didn't even give a thought to doing a Google search. I
remember Dave with fondness. He is and was one of the kindest people I've
ever known (and smart as hell, too!). I recall at one of the clinics in
Salt Lake City when I coveted his McIntosh tie clip. He took it off and
handed it to me. I was and am a dedicated McIntosh fan, probably always
will be.
Again, thanks for sharing this with us.
Harold
Mark Winlund
> "Mark Winlund" <ma...@maxmachine.com> wrote in message
> news:urvtbg7...@corp.supernews.com...
> > Mark (whose stereo comes from Radio Shack)
>
>
> EeuuuUUU...
>
> Hey, I've already made several amps from the junque you gave me.
> What gives?
>
> Tim
I'm afraid my electronics days (and the state of my knowledge) peaked in the
late 60's! I know just enough to sound smart and be dangerous.... when the
boss needs a new stereo, it's off to the mall we go!
Mark
Harold & Susan Vordos
> I think Ted was pointing out that the term "watts RMS" is misleading.
> Taken literally, it means that the number would be calculated as the
> square root of the mean square of the power in watts. It's certainly
> possible to compute this, but it's meaningless for any purpose I know
> of.
>
> But that's not what amplifier manufacturers measure anyway. They
> measure *mean* (average) power in watts over many cycles of the test
> waveform. To do this this measure RMS *voltage* across a resistive load
> and then use the usual V^2/R formula to convert to watts.
>
> The reason they emphasize the "RMS" is that it's also possible to
> calculate "peak power" using the peak voltage of the output waveform.
> For a sine wave, this peak power is twice the mean power, so less
> reputable amp manufacturers used to quote this to make their amps seem
> more powerful than they are.
In the case of McIntosh, I firmly believe that is the reason they specify
RMS. They have always tried to be honest with their products, and I
believe they have been. I understand that power available has little to do
with the useable power available. In my uneducated mind, I assumed that the
RMS was a true and accurate measure of useable wattage without distortion,
which, in a round about way, it apparently is. I had no idea of any other
mehod of measuring actual power, and when it gets right down to it, it
doesn't really tell me much, anyway. It's hell to not understand things,
isn't it?
>
> So measuring peak volts gives you peak power, which is mostly
> meaningless. Measuring RMS volts gives you mean power, which is more
> useful - but it is *not* RMS power. True RMS power is useless.
>
> That's not all there is to power measurement, either - to be meaningful
> the specs have to state what frequency range, what distortion level, and
> what duration the power specifcation applies to. With the Mac amp,
> the specs are probably 300W mean power with sine-wave drive from
> 20-20000 Hz with less than some particular level of distortion and for
> continuous output.
That's exactly how it is specified.
>
> There is also the IHF power standard which attempts to measure the
> capability of an amplifier to amplify a short high-power peak without
> clipping. If the amplifier has regulated power supplies capable of
> maintaining voltage at full output power, this is no higher than the
> continuous rating. But most amps use unregulated power supplies for the
> output stages at least, and when playing music the voltage available is
> quite a bit higher than it would be during a continuous-power test.
> Thus it can often deliver one or a few cycles of higher-power output at
> higher frequencies before the supply voltage droops. This is important
> for being able to reproduce things like percussion instruments.
And it is for this reason that I assume bigger and bigger (in output, not
size) amplifiers continue to be made. The Mc2300 has meters that track,
reasonably well, the power output. Listening with JBL speakers, which are
very efficient as compared to something like Bozak Concert Grand speakers,
something around one watt will fill the room very nicely. Try reproducing
the cannon shots in the 1812, however, and things change, and rapidly. I
assume that a lot of power in reserve must be available to reproduce a sound
like that. I'd buy a 1000 watt amplifier at the drop of a hat. All I
need is the money. I already have the excuse!
Thanks for the great explanation. Now if I could just grasp the meaning
fully! :-)
Harold
>
> Dave
Larry Jaques
<sp...@interlog.com> posted recycled pixels stating:
>The renowned Tim Williams <tmor...@charter.net> wrote:
>> It is now time in this thread to say,
>>
>> WTF IS PMPO!?!?!?!?!?!?!?
>
>Peak Music Power Output. The audio equivalent of "Sears Horsepower" (and
>then some). The magical specsmanship method that allows my offshore "120W"
>computer speakers to be powered from a 9V 200mA AC adapter. ;-)
So it's really Peak Measured Pomposity of the Odvertiser.
============================================================
Help Save the Endangered Plumb Bobs From Becoming Extinct!
http://www.diversify.com/stees.html Hilarious T-shirts online
============================================================
Ted Edwards
> >My 50W amp was designed to be used with 8 ohm speakers so it could put
> >out 20 volts at 2.5 amps into an 8 ohm load. The amp was both voltage
> >limited and current limited for the sake of reliability.
>
> So it will put out 50 W continuous if the waveform is a square wave, but
> it's limited to 25 W of a single-frequency sine wave. Right?
Right. 50W average and 50 watts peak for a square wave, 50 watts peak
and 25 watts average for a sine wave.
One advantage of the peak rating is that it is independent of waveform.
Ted
Ted Edwards
> It should also be noted that if they *do* actually mean RMS power,
While your explanation of a possible scenerio is quite correct, I have
yet to see an amp where the numbers checked out as to that being what
they were doing. Most often they simply lie.
Ted
Ted Edwards
> If you have a sine wave, RMS AC voltage * ... current = true power.
Only if voltage and current are in phase. Into a capacitive or
inductive load there's more to it.
> Huh, I can get at least that much slew rate driving an inductor
> on the breadboard... :)
How is this relevent?
> It seems to me all SS amps of reasonable performance (heck, even modern
> power op-amps, I imagine) use the same complementary PP emitter (or
> source) follower configuration.
There are a couple of emitter follower cofigurations possible. I used
the complimentary EF. A lot of designers used the Darlington.
> Heck, if I had a 'PNP' 6AS7 (or 6C33C :), I'd do it too!
> Instead I've gotta have weird feedback arrangements...oh well.
Just one of the reasons that a tube amp can never real come up to what
is possible with solid state. Another is that mess of copper and iron
that almost all tube amps require.
Ted
Ted Edwards
> For a sine wave, this peak power is twice the mean power, so less
> reputable amp manufacturers used to quote this to make their amps seem
> more powerful than they are.
IF you're lucky. Back in the mid-60s, my neighbour asked me if I would
measure the power out from his new Simpson-Sears solid state stereo. I
tried to talk him out of it but he claimed he REALLY wanted to know.
The output just below clipping on a 1KHz sine wave was 6 watts per
channel. The input power from the 120V line was close to 60 watts.
They haven't changed much, have they.
Ted
Ted Edwards
> Ahem, I'll tell you to shut up right now, as that is an opinion, and
> one that if allowed to get out of hand, well, err I messed that sentence
> up eh.
Yes. Both in grammer and content. How many solid state amps have you
designed and thoroughly tested? How many tube amps have you designed
and thoroughly tested? For how many output transformers have you
plotted phase and frequency properties from 6Hz to 60Khz?
> What undesirables?
If you had done what was asked in the above paragraph, you would know.
> > When FETs came along all the band wagon jumpers wanted to
> > use them everywhere even where they were inappropriate.
> Heh...sounds like tubes eh? ;-) Interestingly, FETs have a similar
> curve to pentodes, don't they.
Similar but they are capable of much more current at much lower voltage
and are available in complementary format. Thus no output transformer
which was one of the most serious design problems in tube amps. Now if
we could get multi-amp pentodes with some using electrons and others
positrons ...
> (Maybe the people are saying something about that curve...heheh)
Ever looked at the collector current vs collector voltage curve of a
junction transistor?
> BTW, Idunno - how's an SCR's negative-resistance characteristic? I know
> they can be used for the same reason (sweep generator), but it just seems
> to me they'd get stuck on. (Not like that didn't happen to me when I set
> the bias too low on said 2D21.)
Check out a tunnel diode.
Ted
Ted Edwards
> Tubes are neat, for some audio applications - I really like my blackface
> Fender Bandmaster...:)
> 45 quite loud watts - rms, peak, or what have you tends to mean less when
> you're overdriving the thing to hell and gone in the first place!
To each his own but that wouldn't qualify as music in my book.
Ted
Larry Jaques
<vor...@tds.net> posted recycled pixels stating:
>ROFLMAO!!!
>
>Have you ever tried to hang a JBL Paragon on rods from the wall? (You do
>know what the Paragon is, don't you?) I run a Paragon and a set of JBL
>C-50 Olympus speakers (S8R components) in tandem. NO way will they fit
>in the travel trailer, and the weight is far greater than I'd like hanging
>off the wall. The combined weight of these speakers is in the
>neighborhood of 700 pounds and they take up over 16 feet of space. I'm so
>crowded that I have the C-50 speakers sitting on top of the Paragon, and the
>electronics sitting on top of the C-50's. It works, but it doesn't replace
>the stereo room, not by a long shot. Oh yeah, the amp weighs in at 128
>pounds. Weight in and of itself limits me to a great extent.
I was thinking about that "generic speaker" statement I made
as I reviewed your "300w" statement, so I laughed with you.
I don't recall the Paragons, but an old friend used to run
a sound and lighting company for rock bands. The only JBLs
I've seen and heard were 18" woofers behind a pair of curved
plywood hornlike guides with a nice 24" multicellular horn
tweeters on top of the 5' tall cabinets. 2 of those on each
side each powered by monaurally linked Phase Linear 700b's
would hammer through the thickest earplug/muff combos I had.
Jussssssst right, when you can feel the sound as much as you
can hear it. <g> That was many moons ago, bwana.
>I thought stacking the components the way I did was being creative! (Where's
>your imagination, dude?) Stop by for a look. We're crowded. REAL
>crowded. :-)
So I "see". Do you use that stereo for vibratory metal
cleaning, or does that take ultrasonic?
>Cool.. Part of my problem in this area is my lack of computer skills.
>I'm constantly going back to correct stupid things. What I know about
>computers wouldn't fill a small thimble. What I am is a machinist that
>loves sound gear. Don't claim to be an electronics expert, but I do the
>best I can. I screw up on the computer, just hope others will be a little
>forgiving of those of us that lack high levels of skills and expertise.
>You seem to qualify! :-)
Thanks. That'll be $76.50 for the consultation. ;)
Tim Williams
news:8481su4196lcener1...@4ax.com...
> >Peak Music Power Output. The audio equivalent of "Sears Horsepower" (and
> >then some). The magical specsmanship method that allows my offshore
"120W"
> >computer speakers to be powered from a 9V 200mA AC adapter. ;-)
>
> So it's really Peak Measured Pomposity of the Odvertiser.
Oh, I see - the acronym is best pronounced holding one's nose.
Tim Williams
> Only if voltage and current are in phase. Into a capacitive or
> inductive load there's more to it.
Let's *really* not get reactive phase angles and vector junk into
this, ok? ;)
> > Huh, I can get at least that much slew rate driving an inductor
> > on the breadboard... :)
>
> How is this relevent?
Absolutely none at all! ;)
> There are a couple of emitter follower cofigurations possible. I used
> the complimentary EF. A lot of designers used the Darlington.
Too bad I don't have many/any PNP transistors, I could at least try
making a 'real' amp. :P
> Just one of the reasons that a tube amp can never real come up to what
> is possible with solid state. Another is that mess of copper and iron
> that almost all tube amps require.
\ / | | /\ --+-- | | |
\ /\ / |---| /__\ | | | |
\/ \/ | | / \ | o o o
We all know it's the PHYSICAL WEIGHT of the amp that makes it sound
good!!!!!!!!!!!
:P
I better duck out of this thread now, I'm getting a distinct bean-counter
impression from you (though you'd almost certainly call it 'practical
engineering' ;).
(If that's your problem, then you could use a switching power supply
for an OTL, you could get low weight and good sound. ;-)
Tim
Bob Chilcoat
Have you ever come across the Carver "Magnetic Field" power amplifiers? I
have an old M-400 that still sounds great, although it's recently developed
some just-audible noise. Described as a "400 watt" amp, but at least there
was never any effort to call that "continuous power". The idea was an amp
that could produce very high peak power for transients ("Max Headroom" - TV
character), but was basically a small (ie cheap) amp. Had some very clever
circuitry that I never fully understood, but I've had excellent enjoyment
from my system (Hafler Preamp, Phase Research Baby R speakers) over the
years.
Bob (Chief Pilot, White Knuckle Airways)
"Ted Edwards" <Te...@telus.net> wrote in message
news:3DC0A2...@telus.net...
Ted Edwards
> I better duck out of this thread now,
You probably should. Facts are irrelevent for you - they will just add
to your frustrations.
> I'm getting a distinct bean-counter
> impression from you (though you'd almost certainly call it 'practical
> engineering' ;).
Let's put it this way. I got into designing my own solid state hi-fi
gear in the early '60s because the best stuff I could get just didn't
sound right when compared to the live symphony orchestra. I should
point out that back then I could hear 22KHz and was used in leu of a
tunning fork or piano when I sang in a choir. I really never enjoyed
Bethoven's symphonies until I built my own gear. I wondered about that
until I looked at the waveform from a violin (Bethoven goes very heavy
on the strings) and found just how much high frequency component is
there and how bad the HF distortion is from most amps. Distortion specs
are almost always stated at mid-band.
I have also recorded a rehersal of a symphony orchestra (Ampex
half-track tape) and played it back later for the conductor. He claimed
it sounded exactly like what he heard at the podium.
> (If that's your problem, then you could use a switching power supply
> for an OTL, you could get low weight and good sound. ;-)
You are the only one who has mentioned weight. The problem with output
transformers is phase response over a broad band. I know, you don't
like vectors and are hoplessly incompetent in math so all you can do is
follow the cult and desperately try to convince yourself that you are
hearing things that aren't there.
> "Hey, back in high school I was voted most likely to be a Hillbilly,
> mental patient or Chimpanzee!"
Sounds about your speed.
Ted
Ted Edwards
> Have you ever come across the Carver "Magnetic Field" power amplifiers?
Yup. Got a hold of a schematic for one way back when. Wasn't overly
impressed. Used lots of trickery to increase headroom for certain parts
of the spectrum, IIRC. Was an effective way to cut cost.
Ted
Bob May
ultimate amount of output power is dependant upon the ability of the power
supplies to provide that power to the output amp. You can lose as much as
10% easily by running the amp at a lower voltage like 110V vs 130V on the
input.
--
Bob May
Global WARMING???
What I want to know is when I can start growing wheat in Greenland again!
Jeffry Johnston
I read the specs for a Carver once and its slew rate was 8 volts
per micro second. I had a junky Sansui that had a real bad case
of crossover notch distortion that was rated at 40 v/micro-s.
With speakers at 100dB/watt/meter any cross over distortion is a
problem. :)
Alvin in AZ
Jeffry Johnston
: > It's an Acoustat (Trans-Nova) twin 200, mos-fet
: > 200 "watts" @ 8 ohms and 325 @ 4 ohms, damping factor over 1000,
: > 165 volt/micro-second slew rate and 400K Hz band width @ -3dB
: > How does it compare to your 50 "real" watter?
: I assume you mean 72 volts rail-to-rail i.e. +/-36V. In this case,
: if it can swing rail-to-rail, that would be 324 peak watts into 4
: ohms or 162 peak watts into 8 ohms.
Actually it's +/-72 volts, so it's a 144 volt rail?
It's not supposed to clip at it's rated power output. The signal
gets ratty but it's supposed to have transient headroom. So with
+/-72v is it 648 watts into 4 ohms and 324 watts into 8 ohms at clip
point? (if what they claim is true "full rail to rail capability")
How does that compare to your 50 "real watter" now? Does it keep up?
What math would you do different to correct their wattage ratings?
(so we can compare the two)
: > The book that goes with it explains how to set the bias and DC
: > offset.
: Hmmmm. A good design should, IMO, not require _any_ user setting
: of these parameters but as long as it works, enjoy!
: Ted
It's one of them snooty power amps. A dumbshit just happened to get
ahold of one cheap because it has a floating ground and the doctor
or lawyer that bought it new messed around and touched the stainless
steel box with the speaker's ground lead. :) It looks like someone
struck an arc with an arc welder on it. :)
It plays for close to a minute after the power is turned off to it.
Internally it's wired with monster cable, I'm not sure the original
build date but I got it in the mid 80's. Acoustat contracted it for
their elctrostatic speakers and their difficult load they present.
Was what I was told by the guy I got it from. Also Hafler bought
them out and used their design but used bipolars in the input instead
of the mos-fets. The same guy told me that years later after he got
one from Hafler.
There, that just may be more than I really -know- about it. ;)
Alvin in AZ
Ted Edwards
> Can you guys explain slew rate and what good it is?
It is the measure of how fast an amp can follow a sudden change in
input.
----------------
|
| Input
----------
-------------
/
/ Output
----------
The slew rate is rate (volts per microsecond) at which the output rises
when trying to follow a step input.
Ted
Mark Winlund
"Ted Edwards" <Te...@telus.net> wrote
> You are the only one who has mentioned weight. The problem with output
> transformers is phase response over a broad band. I know, you don't
> like vectors and are hoplessly incompetent in math so all you can do is
> follow the cult and desperately try to convince yourself that you are
> hearing things that aren't there.
>
> > "Hey, back in high school I was voted most likely to be a Hillbilly,
> > mental patient or Chimpanzee!"
>
> Sounds about your speed.
>
> Ted
>
I suspect that Tim is more competent than you were at his age, and certainly
has surpassed you in manners regardless of *your* age.
Mark
jim rozen
> ----------------
> |
> | Input
>----------
>
> -------------
> /
> / Output
>----------
>
>The slew rate is rate (volts per microsecond) at which the output rises
>when trying to follow a step input.
A step function has a broad spectrum of fourier components.
Those components attenuated above the rolloff frequency of
the amplifier cannot contribute to the output so it gets
rounded over.
You can pretty much guess what the slew rate is going to be,
by knowing the rolloff frequency in an audio amplifier.
Jim
===================================
please reply to:
JRR(zero) at watson dot ibm dot com
===================================
James Wilkins
> > |
> > | Input
> >----------
> >
> > -------------
> > /
> > / Output
> >----------
> Jim
This may be more than anyone who isn't a lab tech or test engineer
wants to know about frequency response errors:
<http://cp.literature.agilent.com/litweb/pdf/5988-6515EN.pdf>
This one's a little easier to follow and shows the relationship
between rise time and bandwidth:
<http://cp.literature.agilent.com/litweb/pdf/5968-2322E.pdf>
jw
Larry Jaques
<tmor...@charter.net> posted recycled pixels stating:
>"Larry Jaques" <lja...@diversify.com> wrote in message
>news:8481su4196lcener1...@4ax.com...
>> >Peak Music Power Output. The audio equivalent of "Sears Horsepower" (and
>> >then some). The magical specsmanship method that allows my offshore
>"120W"
>> >computer speakers to be powered from a 9V 200mA AC adapter. ;-)
>>
>> So it's really Peak Measured Pomposity of the Odvertiser.
>
>Oh, I see - the acronym is best pronounced holding one's nose.
As is the case with this "art". Here's a perfect example
of why I feel that the NEA shouldn't be funded by taxes:
http://www.arts.endow.gov/explore/Gallery/Belichick1.html
Notice that this isn't the first funding for this type of
"art" piece. Well, at least she used stainless bailing wire.
John
Do they still use a square wave to check the amplifier? At one
time this was the best way to check a system. A in theory
square wave can be be generated by a number of sine waves (don't
remember the exact formulas any more) and if the amp will pass a
10 kc square wave it will handle a sine wave of 10 times the
square wave freq.
John
Ted Edwards
> A step function has a broad spectrum of fourier components.
> Those components attenuated above the rolloff frequency of
> the amplifier cannot contribute to the output so it gets
> rounded over.
>
> You can pretty much guess what the slew rate is going to be,
> by knowing the rolloff frequency in an audio amplifier.
You are confusing rise time and slew rate. Rise time is, indeed,
predictable from frequency response. It is a linear thing - i.e. twice
the input amplitude gives twice the output with the same 10% to 90% rise
time.
Slew rate is a non-linear thing. Once the input step amplitude exceeds
a certain amount, the amp will try to catch up at its slew rate.
increasing the input step amplitude will not materialy effect the output
slope.
If you feed a square wave of meduium to low frequency into an amp (a
series of + and - steps), and slowly increase the amplitude while
watching on a scope, you will see that the shapes (scaled output
compared to input) stay the same up to a certain amplitude where slewing
takes over from rise time.
Ted
Ted Edwards
> Do they still use a square wave to check the amplifier? At one
> time this was the best way to check a system. A in theory
> square wave can be be generated by a number of sine waves (don't
> remember the exact formulas any more) and if the amp will pass a
> 10 kc square wave it will handle a sine wave of 10 times the
> square wave freq.
Square wave testing is still useful but is only one of many tests.
There's more to it than just "pass" and "handle". but, without getting
into the math, a usefull approximation is that the product of the 3db
upper cutoff frequency and the rise time will be approximately 0.3. An
amp with a 100KHz upper cutoff should have a rise time on the order of 3
microseconds.
Ted
Michael T. Kasimirsky
> of why I feel that the NEA shouldn't be funded by taxes:
>
> http://www.arts.endow.gov/explore/Gallery/Belichick1.html
Walked around The Carnegie in Pittsburgh and all I could think
of when in the "modern art gallery" section was "what a total pile
of crap this stuff is." I can't believe that 1) people make that crap
and think it's "art," and 2) other people find it enjoyable to look
at a pile of crap from Home Depot that some joker spent a month
hot glueing together in abstract shapes.
Some folks use wire nuts to create art. I use them to hold two
wires together. Maybe it's just me.
Ted Edwards
> > As is the case with this "art". Here's a perfect example
> > of why I feel that the NEA shouldn't be funded by taxes:
> > http://www.arts.endow.gov/explore/Gallery/Belichick1.html
> Walked around The Carnegie in Pittsburgh and all I could think
> of when in the "modern art gallery" section was "what a total pile
> of crap this stuff is." I can't believe that 1) people make that crap
> and think it's "art," and 2) other people find it enjoyable to look
> at a pile of crap from Home Depot that some joker spent a month
> hot glueing together in abstract shapes.
IMO. much abstract art has the distinct advantage of not requiring any
skill to create.
One summer in the late '50s or early '60s (I forget which) there was an
exhibitiom of "Modern Sculpture" on the U.B.C. lawn. Pieces were placed
on
the grass and every few days some were removed and new ones put in their
place. Frankly, I, for one, was monumentally underwhelmed.
Then, one day we arrived on campus to see all the pieces smashed to
bits.
Needless to say, there was a great hue and cry. Talk of vandalism, law
suits
and jail terms. Newspaper headlines and outcries to disband the
Engineering
Undergraduate Society who was _assumed_ to be the responsible party.
After about a week of the arty community getting there drawers in a knot
and
police investigations and ..., the truth finally emerged.
It seems that on the evening of the last day of the show trucks had
arrived to
take away the remaining sculptures. No sooner had they dissapeared from
sight
than a number of cars and trucks showed up and unloaded a bunch of
concrete
blobs that the Engineers had prepared. These remained on site for a few
days
when the "vandels" returned and smashed there own junk to bits.
Needless to say when the whole story came out, there were some very red
faces
in the local arts community.
I know this story to be true as I was on campus at the time. I had not
particularly noticed any decline in the "artistic quality" of the
exhibits
during the "extended" exhibit.
Ted
Tim Williams
news:fNBw9.40387$Lg2.10...@news2.news.adelphia.net...
> Walked around The Carnegie in Pittsburgh and all I could think
> of when in the "modern art gallery" section was "what a total pile
> of crap this stuff is." I can't believe that 1) people make that crap
> and think it's "art," and 2) other people find it enjoyable to look
> at a pile of crap from Home Depot that some joker spent a month
> hot glueing together in abstract shapes.
Cletus the Slack-jawed Yokel once said:
"Hey, I dun studied fo' years on how to get o'er that junkyard fence!
Then I learn't the gate was op'n."
James Waldby
...
> Walked around The Carnegie in Pittsburgh and all I could think
> of when in the "modern art gallery" section was "what a total pile
> of crap this stuff is." I can't believe that 1) people make that crap
> and think it's "art," and 2) other people find it enjoyable to look
> at a pile of crap from Home Depot that some joker spent a month
> hot glueing together in abstract shapes.
I must have missed the modern art gallery when I took in the
Carnegie Museum last January, so I didn't have that reaction
at all. :) I hadn't been in a museum with mammoth skeletons
before, much less multiple species of them.
A really good museum for metalworkers is the Philadelphia
art museum. Several dozen suits of armor, thousands of
helmets, swords, pikes, halberds. Chain mail with a
myriad of tiny rivets. Mostly medieval, but there's a
fair number of Roman and Greek helmets, and a few Phoenician
ones. In an adjacent room are hundreds of guns from
around Renaissance times through the 1800's.
-jiw
Gary Coffman
>Can you guys explain slew rate and what good it is?
Slew rate is a measure of an amplifier's ability to faithfully follow large signal
excursions. To an extent, it is the large signal equivalent of the amplifier's
small signal bandwidth and open loop gain performance.
Gary
Gary Coffman
>You can pretty much guess what the slew rate is going to be,
>by knowing the rolloff frequency in an audio amplifier.
Not necessarily. Slew rate is a function of the combination of bandwidth
and open loop gain. An amp with a wide bandwidth but low open loop
gain will have a lower slew rate than one with a higher open loop gain.
Gary
Gary Coffman
>Gary Coffman wrote:
>
>> McIntosh rates their amps in terms of "RMS power". Now as a physicist
>> will tell you, that's a nonsense term. But what it means in the audio world
>> is that their power ratings are the *average power* for *continuous pure
>> sinewave signals* (which can be calculated using RMS values for voltage
>> or current, hence the term). In effect that's the same thing that Ted is saying
>> when he says his amp can maintain 50 watts "peak output indefinitely".
>
>Except that the IHFM standard uses tone bursts and other cheats - see my
>post elsewhere in this thread. I've never had a commercial amp on the
>bench that could maintain its maximum rated output for more than a few
>milliseconds and damn few that could reach their rated output at all.
Then you've never seen a McIntosh or Crown amp.
>> It is pretty safe to say that an IHF rated 1000 watt amp would be *much*
>> wimpier than a 1000 watt RMS rated amp.
>
>I assume you mean AVERAGE not RMS.
I'm using RMS rating the way McIntosh uses it. As explained above, it is
the power available for a continuous pure sinewave signal. Since that's
the RMS voltage squared divided by load resistance, it is the same thing
as average power when measuring a continuous sinewave signal. This
is what McIntosh, Crown, and a few other amplifier manufacturers mean
by this term.
>> difference down in the bass region. The RMS rated amp will have much
>> more guts there for delivering sustained power, and it'll clearly show in a
>> listening test.
>
>If it was honest, it would not likely be using the term RMS power. If
>it isn't honest then, ... .
Get over it. I've already explained the industry's usage of this term more
than enough times.
Gary
Dave Martindale
>I'm using RMS rating the way McIntosh uses it. As explained above, it is
>the power available for a continuous pure sinewave signal. Since that's
>the RMS voltage squared divided by load resistance, it is the same thing
>as average power when measuring a continuous sinewave signal. This
>is what McIntosh, Crown, and a few other amplifier manufacturers mean
>by this term.
Ok, but why do they call it that? It simply is not RMS power, it's mean
power calculated using RMS voltage. There *must* be engineers at these
companies that know the difference between mean power and RMS power.
So why use an obviously incorrect term?
Dave